Snow melting system and method with direct-contact water heater

ABSTRACT

A snow melting system and a method is comprised of a snow melting housing defining a snow melting chamber therein. The housing has an opening to load snow in the snow melting chamber. A support is provided across the snow melting chamber to support snow therein elevated from a bottom wall of the snow melting chamber and to permit the passage of water therethrough to be collected in a water holding portion of the housing. A plurality of water spray nozzles are mounted in the housing about the snow melting chamber. A direct-contact water heater is provided for heating water to produce a supply of hot water to be fed at a constant pressure to the water spray nozzles for injection into the snow placed in the snow melting chamber for melting the snow. The direct-contact water heater is supplied water to be heated from the water holding portion of the housing. Excess water in the water holding portion is discharged and disposed of in the city drainage system.

TECHNICAL FIELD

The present invention relates to a snow melting system and its method of operation and particularly one which utilizes a direct-contact water heater to supply hot water to water jets disposed about a snow melting chamber for injection into snow placed therein.

BACKGROUND ART

Various types of snow melting systems are known for melting snow placed in a container and disposing of the water accumulating from the melted snow. However, such known devices lack in fuel efficiency and cannot achieve high melting rates per unit of fuel consumed or electricity used. They are therefore expensive to operate. Some of these devices are also very bulky and troublesome and require excessive maintenance to defrost the unit during cold weather periods when these units are not in use.

Such devices have been designed to overcome the disadvantage of common snow removal methods used in large cities wherein large quantities of snow are stockpiled on the side of streets and parking lots or on large stock piling lots. The stacked snow results in an inefficient use of space resulting in the narrowing of streets, a decrease in vacant parking spaces which can be hazardous as it decreases visibility. Also, parking spaces which use parking meters cannot be employed while large snow banks may be left in place for several days. The transport of the snow is also expensive. Depending on how severe winter is, snow piles can end up staying weeks or sometimes months in the same space.

A more effective means of snow removal is to eliminate the snow banks by melting the snow immediately or within a short period of time. The snow melting technologies developed to suit this purpose consist of large melting systems where the snow is melted and then drained into the city's drainage system. Such technologies include emersion burners and submerged combustion with energy sources such as electricity, oil, propane and natural gas. A disadvantage of these known systems is that they produce fog which causes ice to build up in the vicinity of the systems and this has also proven to be hazardous and can also affect the proper operation of the snow melting apparatus in that ice can build up around valves preventing the operation thereof.

Reference is made to U.S. Pat. No. 5,791,335 which teaches an apparatus for melting snow. It comprises a hopper which has a lower trough. A screen is provided in the central area of the hopper to prevent large debris from passing to the trough thereunder. Melted snow, in the form of slush, is mixed with the water in the trough and pumped into a furnace for melting. The hot water in the furnace is then sprayed on the centralized snow debris introduced in the hopper. This system poses several disadvantages in that snow can pass around the screen and into the trough and often debris can be found in the trough. The snow can also clog the exit port of the trough, particularly if debris is directed thereto, such as paper, cardboard and the like clogging material.

Another disadvantage of this apparatus is that the waterlines leading to the water jets can freeze if the device is left outside and not used. Accordingly, the device must be defrosted in a garage for re-use. The pivoting screen is also a troublesome design and can also freeze up. This type of open-ended device also produces an excess quantity of fog in the immediate area thereof particularly when the hot water is sprayed over the snow. The fog causes the ground to ice-up, making it hazardous to the snow loading equipment and nearby traffic.

SUMMARY OF INVENTION

It is a feature of the present invention to provide a compact snow melting system and method which uses a high efficiency direct-contact water heater to produce hot water and wherein the hot water is injected, at a substantially constant pressure, into the snow contained in a snow melting housing.

Another feature of the present invention is to provide a snow melting system and method wherein hot water is injected by water nozzles directly into the snow thereby causing very little fog or vapour released from the snow.

Another feature of the present invention is to provide a snow melting system which may be a stationary or a mobile system.

Another feature of the present invention is to provide a snow melting system and method wherein substantially all unwanted debris is filtered from the snow and wherein the system can perform at close to 100 percent efficiency.

Another feature of the present invention is to provide a snow melting system and method and wherein the hot water temperatures are produced in a substantially constant temperature range and wherein the supply of water to the direct-contact water heater is achieved in a closed loop of the system.

According to the above features, from a broad aspect, the present invention provides a snow melting system which comprises a snow melting housing defining therein a snow melting chamber. An opening is provided in the housing to load snow in the snow melting chamber. Support means is provided across the snow melting chamber to support snow therein elevated from a bottom wall of the snow melting chamber and permitting the passage of water therethrough to be collected in a water holding portion of the housing. A plurality of water spray nozzles are mounted in the housing about the snow melting chamber. A direct-contact water heater is provided for heating water to produce a supply of hot water to be fed at a constant pressure to the water spray nozzles for injection into snow placed in the snow melting chamber for melting the snow. The direct-contact water heater is supplied water to be heated from the water holding portion of the housing. Water evacuation means is provided to discharge excess water from the water holding portion.

According to a further broad aspect of the present invention there is provided a method of melting snow for disposal thereof. The method comprises the steps of discharging snow to be melted into a snow melting chamber of a snow melting housing. The snow is supported in the housing elevated from a bottom wall thereof by support means permitting the passage of water therethrough. Hot water is injected in the snow by water spray nozzles secured all about the snow melting chamber and at a constant pressure whereby to melt the snow at a substantially constant rate. The water produced from the melted snow is collected in a lower water holding portion of the housing. Excess water is evacuated from the lower water holding portion for disposal. Water from the lower water holding portion is also recirculated to a direct-contact water heater to heat the water therein to produce a source of hot water to supply the water spray nozzles.

BRIEF DESCRIPTION OF DRAWINGS

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a schematic view showing the construction of the snow melting system of the present invention; and

FIG. 2 is a perspective view showing the snow melting system of the present invention when in use as a stationary system.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings and more particularly to FIG. 1, there is shown generally at 10 the snow melting system of the present invention. It is comprised of a snow melting housing 11 which can have many forms such as a stationary bin 11′ as shown in FIG. 2 or that bin or other housing could be mounted on a transport vehicle together with its associated equipment. The snow melting housing 11 defines therein a snow melting chamber 12 extending from above a support screen 14 which extends across the opposed side walls 15 of the housing 11 whereby to filter out debris 16 collected with the snow 13. The housing 11 has an open top end 17 to load snow into the snow melting chamber 12. The open top end 17 can also be provided with a suitable closure, not shown.

As hereinshown a plurality of water spray nozzles 18 are mounted in the housing side walls 15 all about the snow melting chamber 12. These water spray nozzles 18 have their jets 19 oriented upwardly at a slight angle whereby to inject a hot water spray 20 inside the snow 13 loaded into the snow melting chamber 12 whereby to minimize the creation of vapour or fog emitting from the snow 13 as it is melted. Water produced from the melted snow will seep through the support screen 14 and collect in a water holding portion or reservoir portion 21 of the snow melting housing 11. The snow melts at a substantially constant rate due to the high temperature of the hot water and the constant pressure of the pump 38. Accordingly, the snow cleaning operation is continuous due to the fast melting rate of the snow.

The system of the present invention also utilizes a direct-contact water heater 25 which consists essentially of a heating housing, herein provided as a cylindrical vertical column 25 provided with one or more spray nozzles 26 at a top end thereof and spaced above a packing 27 of heat exchange bodies. Such direct-contact water heaters are well known in the art and can have different shapes and one or more packings.

A recirculating pump 28 pumps water from the water holding portion or reservoir 21 of the snow melting housing 11 to the spray nozzle 26 of the direct contact water heater via the conduit 29. This water spray percolates over heat exchange bodies 30 which form the packing 27 whereby the sprayed water percolates through these heat exchanger bodies to extract heat therefrom. A burner 31, herein a natural gas, oil or propane gas burner, is mounted on the housing 33 of the direct-contact water heater 25 and spaced below the packing 27. The gas burner 31, herein a natural gas burner, produces a hot flame 32 into the housing 33 to generate a heating air flow in the direction of arrow 34 to heat the heat exchange bodies 30 and to heat the water droplets 35 released from underneath the packing 27. These droplets are heated by the hot convection air flow 34 and the flame 32 and collect as hot water in a collecting reservoir 36 at the bottom end of the housing 33 whereby to constitute a supply of hot water. The water in the reservoir is at a temperature of about 40° C. to 50° C. The recirculated water in the conduit 29 and injected by the spray nozzle 26 is at a temperature of about 3° C. to 4° C. Accordingly, it can be appreciated that such a water heater is a very efficient water heater and operates in a continuous closed loop. The hot gas temperature a burner discharge is approximately 1540° C.+and exhaust after heat exchange at 10° C.

As further shown in FIG. 1, the water spray nozzles 18 are mounted in multiple vertical rows, only two being shown herein, all about the side wall 15 in the snow melting chamber 12. Each vertical row is hereinshown consisting of two spray nozzles 18 and 18′. Accordingly, they form two horizontally spaced rows of spray nozzles about the snow melting chamber and each of the nozzles in each horizontal row is fed the hot water from the reservoir 36 by a constant pressure pump 38 whereby to inject the hot water into the snow 13. The operation of the water spray nozzles 18 in each of the horizontal rows 18 and 18′ can be switched on or off by the use of valves 39 and 39′, respectively, and depending on the amount of snow or rate of snow being discharged within the snow melting chamber 12. As shown in FIG. 1, a further filter 40 can be interposed between the water holding portion or reservoir 21 of the snow melting housing 11 and the recirulating pump 28. The direct-contact water heater is also provided with an evacuation conduit 41 to evacuate the fumes produced by the gas burner.

As shown in FIG. 2, the snow melting system herein illustrated utilizes a stationary bin 11′ which can be mounted at a convenient location, such as in the parking lot of a large shopping complex. Accordingly, the direct-contact water heater would be mounted in a housing, not shown, and most likely supplied natural gas from a natural gas line of a building of such shopping complex. As shown in FIG. 2, snow is unloaded into the snow melting housing 11 by a front end loading vehicle 42 provided with a bucket 43 capable of containing a large quantity of snow 13 and to discharge same within the open top end 17 of the bin 11′. Accordingly, snow is not stock-piled in the parking lot of the establishment and as it is picked up by the front loading vehicle 42, it is immediately melted at a rapid rate to ensure a continuous loading process. Excess water from the water holding portion or reservoir 21 of the snow melting housing 11 is evacuated therefrom by suitable means for discharge into the city drainage system, and such is indicated by the discharge line or trough schematically shown at 44 in FIG. 1. A flexible discharge pipe can also be used with one end of the pipe being positioned down into a city sewer manhole.

It can be appreciated from FIG. 1 that the system as herein-described consists of a closed loop system wherein hot water is produced from the melted snow by recirculating the water through a direct-contact water heater to produce very hot water whereby snow can be melted quickly. Such a system also utilizes large flexible conduits 45 which can be drained quite easily when not in use thereby preventing freezing.

Briefly summarizing the method of operation of the snow melting system 10 as illustrated in FIGS. 1 and 2, it comprises the steps of discharging snow to be melted in the snow melting chamber 12 of the snow melting housing with the snow supported therein elevated from a bottom wall 11′ of the housing. The snow is supported by a filter screen 14 whereby to remove debris 16 which may have collected in the snow 13. Hot water jets are injected into the snow by water nozzles 18 all about the snow melting chamber and at a constant pressure whereby to melt the snow at a substantially constant fast rate. Water from the melted snow is collected in the lower water holding portion or reservoir 21 of the housing 11 and pumped back to the direct-contact water heater 21 for heating. Excess water in the lower water holding portion or reservoir 21 is evacuated through the discharge line 44 for disposal in the city drainage system. The recirculated water in the conduit 29 is injected over a heat exchange packing 27 of the direct-contact water heater 25 whereby to extract heat and collect in a reservoir 36 wherein the temperature of the water has increased from 4° C at the spray nozzle 26 to about 40 to 50° C. in the collecting reservoir 36. This hot water is then injected in the snow by the spray nozzles 18 and the system is continuous in a closed loop. After use the debris 16 collected on the screen 14 is removed.

It is within the ambit of the present invention to cover any obvious modifications of the preferred embodiment described herein provided such modifications fall within the scope of the appended claims. 

1. A snow melting system comprising a snow melting housing defining therein a snow melting chamber, an opening in said housing to load snow in said snow melting chamber, support means across said snow melting chamber to support snow therein elevated from a bottom wall of said snow melting chamber and permitting the passage of water therethrough to be collected in a water holding portion of said housing, a plurality of water spray nozzles mounted in said housing about said snow melting chamber, a direct-contact water heater for heating water to produce a supply of hot water to be fed at a constant pressure to said water spray nozzles for injection into snow placed in said snow melting chamber for melting said snow, said direct-contact water heater being supplied water to be heated from said water holding portion of said housing, and water evacuation means to discharge excess water from said water holding portion.
 2. A snow melting system as claimed in claim 1 wherein said support means is a filter screen for removing debris from snow melted in said snow melting chamber.
 3. A snow melting system as claimed in claim 1 wherein there are multiple vertical rows of said water spray nozzles mounted about said snow melting chamber.
 4. A snow melting system as claimed in claim 1 wherein said water spray nozzles are angulated in an upward direction in said snow melting chamber and wherein a supply of snow is maintained to at least cover said water spray nozzles to reduce the production of vapour from said hot water injected in said snow in said snow melting chamber.
 5. A snow melting system as claimed in claim 1 wherein said direct-contact water heater is comprised of a heating housing having one or more spray nozzles at a top end thereof spaced above a packing of heat exchange bodies, said one or more spray nozzles spraying said water to be heated over said packing in water droplets to cause said water droplets to percolate through said heat exchange bodies to extract heat therefrom, a burner spaced below said packing exteriorly of said heating housing and adapted to introduce a hot flame in said heating housing spaced below said packing to generate a heating air flow for heating said heat exchange bodies and further heating said water droplets released from underneath said packing, and a hot water collecting reservoir at a bottom end of said heating chamber constituting said supply of hot water.
 6. A snow melting system as claimed in claim 5 wherein said burner is one of a natural gas, propane gas or oil burner being supplied by a supply source.
 7. A snow melting system as claimed in claim 5 wherein said supply of hot water is fed under substantially constant pressure to said water spray nozzle by a transfer pump, and valve means to connect selected groups of said water spray nozzles to said transfer pump.
 8. A snow melting system as claimed in claim 5 wherein said one or more spray nozzles are fed said water to be heated from said water holding portion of said housing by a water re-circulation pump.
 9. A snow melting system as claimed in claim 8 wherein a further filter is connected in an outlet conduit of said water holding portion of said housing upstream of said water re-circulation pump.
 10. A snow melting system as claimed in claim 5 wherein said supply of hot water is at a temperature of from about 40° C. to 50° C., said water to be heated in said water holding portion of said housing being at a temperature of about 3° C. to 4° C.
 11. A snow melting system as claimed in claim 1 wherein said apparatus is one of a stationary or a mobile snow melting housing.
 12. A snow melting system as claimed in claim 1 wherein said water evacuation means is an overflow conduit connected to said housing in a top portion of said water holding portion to direct excess water therefrom for disposal in a drainage system.
 13. A method of melting snow for disposal thereof comprising the steps of: i) discharging snow to be melted into a snow melting chamber of a snow melting housing, said snow being supported therein elevated from a bottom wall of said housing by support means permitting the passage of water therethrough, ii) injecting hot water by water spray nozzles secured all about said snow melting chamber in said snow and at a constant pressure whereby to melt said snow at a substantially constant rate, iii) collecting water from said melted snow in a lower water holding portion of said housing, iv) evacuating excess water from said lower water holding portion for disposal, v) recirculating water from said lower water holding portion through a direct-contact water heater to heat said water therein to produce a source of said hot water to supply said water spray nozzles.
 14. A method as claimed in claim 13 wherein said support means is a screen and wherein there is further provided the step of separating debris from said snow by said screen as said snow is being melted in said snow melting chamber, and removing said debris from said screen.
 15. A method as claimed in claim 13 wherein said step (v) comprises pumping said water from said lower water holding portion to one or more spray nozzles at a top end of said direct-contact water heater, spraying said water by said spray nozzles over a packing of heat exchange bodies to form water droplets for heat exchange therewith to heat said water droplets percolating therethrough, injecting a flame from a burner below said packing to generate a hot air flow through said packing to heat said heat exchange bodies and further heat water droplets released from underneath said packing, and collecting said heated water droplets in a collecting reservoir therebelow.
 16. A method as claimed in claim 13 wherein said step (iv) comprises evacuating an overflow of water from said lower holding portion and feeding same into a drainage system.
 17. A method as claimed in claim 13 wherein said water spray nozzles are equidistantly spaced about said snow melting chamber in at least two horizontal rows and wherein said step (ii) further comprises the step of connecting one or both of said at least two horizontal rows of water spray nozzles to a constant pressure pump to inject said hot water through said one or both horizontal rows of water spray nozzles, said water spray nozzles being oriented to inject said hot water directly into said snow to minimize the formation of vapour above said snow. 